1. Field of the Invention
The present invention relates to piping systems for the transportation of toxic and hazardous fluids and more particularly to an apparatus and method for providing secondary containment of fluids in a portion of a piping system having a fluid regulation control device.
2. Description of the Related Art
Over the years, the transport of toxic and hazardous fluids, particularly gases, such as nitrogen, argon, hydrogen, oxygen, silane, phosphine, arsine, and/or various mixed gases, via piping systems, has presented a serious problem for engineers, contractors and others who use or effect transportation of these fluids. When piping systems are used to transport such fluids from one point to another including through or between fluid regulation control devices, such as valves or purge tees, there exists the possibility of a leak occurring in the piping system, thereby allowing hazardous or toxic gases to escape. The resulting risk of death or sickness resulting from inhalation of gases by persons near the piping system, or an explosion should the escape or incendiary fluids ignite has led to stricter OSHA requirements for these piping systems, particularly the requirement of some form of secondary containment.
In partial response to this problem, present applicant has developed a coaxial piping system disclosed in present applicant's co-pending U.S. patent application entitled "Coaxial Piping System", Ser. No. 07/122,537. Ser. No. 7/122,537 is a continuation application of U.S. patent application Ser. No. 06/937,441, now abandoned, of the same title which is a continuation application of U.S. patent application Ser. No. 06/809,584, now abandoned. Briefly, the coaxial piping system disclosed in those patent applications includes an outer conduit, an inner conduit disposed within the outer conduit along the longitudinal axis thereof, and a spacer helically wound about the inner conduit for centering the inner conduit within the outer conduit and permitting fluid flow through the volume between the inner conduit and the outer conduit such that gas traveling through that volume and around the spacer disperses and evenly mixes with the pockets of fluid present in that volume. The spacer also prevents crimping of the inner conduit when the coaxial piping system is bent to conform to the desired geometry of the piping system. Thus, although presenting a partial solution to the need of providing secondary containment, the requirement for secondary containment about fluid regulation control devices, such as valves, disposed about portions of the piping systems, has remained unresolved.
U.S. Pat. No. 2,649,769 issued to E. W. Kaiser entitled "Jacketed Valve", discloses a jacketed valve comprising a valve casing housing having outwardly, openly, and inter-communicating ways therein. The valve casing housing preferably consists of a pair of complementary shaped and sized T-shaped sections. One of the ways is angularly disposed with relation to the others. A valve casing in the housing ways is spaced from the side walls thereof. A cover plate having an opening therein is engaged with the housing over the open outer end of the angularly disposed way. A stuffing box on the cover is cooperatively associated with the cover opening, and a valve stem bonnet connected at one end to the valve casing and extended therefrom into the angularly disposed way and through and beyond the opening in the cover plate and stuffing box is fixedly and supportingly engaged by the stuffing box.
U.S. Pat. No. 3,323,541, issued to T. E. Schneider, Jr., et. al., entitled "Safety Device For Gas Cylinders", discloses a safety device for a gas cylinder of the type providing an externally threaded nub supporting a gas discharge valve and a surrounding area beyond the nub. The safety device includes an internal anchor chamber, internal threads formed on the anchor chamber for threadedly engaging the external threads of the nub to secure the anchor chamber to the nub, an external sealing chamber enclosing the internal anchor chamber, the external sealing chamber defining an open end edge sealingly engageable in abutting relationship with the surrounding area of the cylinder beyond the nub. A threadedly adjustable interconnection is provided between the internal anchor chamber and the external sealing chamber for operably adjusting the location of the external sealing chamber with respect to the internal anchor chamber to force the open end edge of the external sealing chamber in sealing engagement with the surrounding area of the cylinder beyond the nub.
U.S. Pat. No. 3,291,148, issued to C. W. Sloan, et. al., entitled "Tamper Proof Enclosure For Flush Valves", discloses an enclosure for the flush valve for a water flushing system. The water flushing system is of the type having a valve body with a tubular threaded inlet connection, and a tubular threaded outlet connection lying in a plane perpendicular to the plane of the inlet connection; a discharge pipe connected to the outlet connection by a pipe union; a valve mechanism housed in the body between the inlet and outlet connections; a valve actuating member extending outwardly from the body; and, a mounting for the valve actuating member carried by the body.
The enclosure for the particular water flushing system described in that patent reference comprises a shell divided longitudinally into an upper shell portion and a lower shell portion having mating rims arranged and adapted to be brought together to form a unitary casing housing for the valve. The lower shell portion has an opening for the outlet connection and a valve around the opening engageable between the pipe union and the valve body adjacent the outlet connection so that the lower shell portion is secured to and supported by the valve body, complemental inter-engaging fastening means carried by the rims, complemental recesses in the rims of the upper and lower shell portion forming an opening for the mounting for the inlet pipe. One of the openings has a collar formed by complemental portions formed on the upper and lower shell portions. A removable locking member engages the collar and the valve body, the locking member and the inter-engaging fastening means cooperating to retain the casing as a unitary assembly to secure it to the valve body.
U.S. Pat. No. 3,965,916, issued to G. Karis, entitled "Apparatus and Method for Gagging a Relief Valve within a Flue Secured to a Tank" discloses an apparatus including an elongated cylindrical body removably secured into a load-transferring position. An elongated structural member is adjustably extended through this elongated body to a load-transferring position against the upper head of the valve assembly. Consequently, the cylindrical body and structural member gags the valve assembly either by preventing movement of the spring restrained upper end from moving off its seat or by pushing the valve head against the seat if the spring cannot.
U.S. Pat. No. 4,540,019, issued to J. R. Owoc, et. al., entitled "Bellows Sealed Stem for a Rotary Valve", discloses a rotary valve having a bent valve stem enclosed and hermetically sealed by a bent bellows which is internally pressurized during operation of the valve and supported substantially along its entire length by the valve stem to resist lateral deflection and distortion of the bellows and thereby prevent failure of the bellows seal.
U.S. Pat. No. 1,541,801, issued to R. E. Durning, entitled "Valve Lock", discloses a valve lock and enclosing casing having an upwardly disposed neck. A U-shaped member is formed thereon provided with transverse perforations. A valve stem drum is rotatably mounted in the casing neck and a locking key is provided, having a recess formed complementary to the U-shaped member perforations. Locking means is provided, passing through the key and U-shaped member for holding the key in locked position.
U.S. Pat. No. 2,206,707, issued to R. D. Shaw, entitled "Sealing Device", discloses, in combination with a casing structure having an element extending therefrom along which leakage of fluid from the interior of the casing may occur, a sealing means comprising an annular member fused to the casing. The member has lugs with centering pins on diametrically opposite portions. A sealing ring engaging the member and centered on the pins is included in a cup for enclosing such element and sealing it to the annular member. The cup has a flange with lugs engaging the sealing ring and centered on the pins. Means are provided for forcing the cup into fluid tight engagement with the sealing ring and the annular member. Such means comprises a U-shaped yoke having legs pivotly connected to diametrically opposite portions of the casing structure.
Thus, from the above descriptions, it can be seen that prior art methods of attempting to solve the problem of secondary containment of valves, and the like, in piping systems has generally included the use of complicated, expensive devices. Furthermore, these devices are typically specific to a particular valve and cannot be easily integrated into an existing piping system.
As will be disclosed below, the present invention provides an improved apparatus and method for secondary containment which overcomes the disadvantages of the prior art by providing a structure which can be easily assembled about conventional valves, and the like. In addition, the present invention is particularly adaptable to the coaxial piping system disclosed in present applicant's earlier applications.